Remove sketchy state DCHECK from ConsensusQueue
Remove sketchy state DCHECK from ConsensusQueue

I hit this check in RaftConsensusQuorumTest.TestConsensusContinuesIfAMinorityFallsBehind
and it seems pretty sketchy in a shutdown scenario. Let's just assert
that we are not in an uninitialized state and put the "is open" check in
an if statement instead.

I0513 02:47:11.692281 32369 raft_consensus.cc:1028] T TestTablet P peer-2 [term 1 LEADER]: Raft consensus shutting down.
F0513 02:47:11.692584  2142 consensus_queue.cc:391] Check failed: queue_state_.state == kQueueOpen (2 vs. 1)
*** Check failure stack trace: ***
*** Aborted at 1431510431 (unix time) try "date -d @1431510431" if you are using GNU date ***
PC: @     0x7f7c8408acc9 (unknown)
*** SIGABRT (@0x3e800007e71) received by PID 32369 (TID 0x7f7c769b4700) from PID 32369; stack trace: ***
    @     0x7f7c86ff7340 (unknown) at ??:0
    @     0x7f7c8408acc9 (unknown) at ??:0
    @     0x7f7c8408e0d8 (unknown) at ??:0
    @     0x7f7c8c96cd39 google::logging_fail() at ??:0
    @     0x7f7c8c96e38d google::LogMessage::Fail() at ??:0
    @     0x7f7c8c97022d google::LogMessage::SendToLog() at ??:0
    @     0x7f7c8c96df7c google::LogMessage::Flush() at ??:0
    @     0x7f7c8c970b4e google::LogMessageFatal::~LogMessageFatal() at ??:0
    @     0x7f7c8c1a56fe kudu::consensus::PeerMessageQueue::ResponseFromPeer() at ??:0
    @     0x7f7c8c1a0711 kudu::consensus::PeerMessageQueue::LocalPeerAppendFinished() at ??:0
    @     0x7f7c8c1c0f5c kudu::internal::InvokeHelper<>::MakeItSo() at ??:0
    @     0x7f7c8c1c0d75 kudu::internal::Invoker<>::Run() at ??:0
    @     0x7f7c8c1efb8f kudu::consensus::LogCache::LogCallback() at ??:0
    @     0x7f7c8c1fa9de kudu::internal::InvokeHelper<>::MakeItSo() at ??:0
    @     0x7f7c8c1fa6e8 kudu::internal::Invoker<>::Run() at ??:0
    @     0x7f7c8c603a7f kudu::log::Log::AppendThread::RunThread() at ??:0
    @     0x7f7c8c62ebdc boost::_bi::bind_t<>::operator()() at ??:0
    @     0x7f7c89a73beb boost::function0<>::operator()() at ??:0
    @     0x7f7c89af8078 kudu::Thread::SuperviseThread() at ??:0
    @     0x7f7c86fef182 start_thread at ??:0

Change-Id: I9f8f07196db969a459b166e0ea92c26285e045fe
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/6628
Tested-by: jenkins
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@cloudera.com>

cloudera/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,InspurUSA/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,andrwng/kudu,andrwng/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,cloudera/kudu,cloudera/kudu,cloudera/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,InspurUSA/kudu,cloudera/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,helifu/kudu,cloudera/kudu,InspurUSA/kudu,helifu/kudu,andrwng/kudu,EvilMcJerkface/kudu,helifu/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,cloudera/kudu,EvilMcJerkface/kudu,andrwng/kudu,helifu/kudu,EvilMcJerkface/kudu,andrwng/kudu,InspurUSA/kudu,helifu/kudu,andrwng/kudu